Method and apparatus for forming and driving an improved staple



Nov. 25, 1958 G. H. REED 2,851,269

METHOD AND APPARATUS FOR FORMINGAND Y DRIVING AN IMPROVED STAPLE Filed June 19, 1952 5 Sheets-Sheet 1 MQDM,

Nov. 25, 1958 G. H. REED 2,861,269

METHOD AND APPARATUS FOR FORMING AND DRIVING AN IMPROVED STAPLE Filed June 19. 1952 5 Sheets-Sheet 2 Nov. 25, 1958 G. H. REED METHOD AND APPARATUS FDR FORMING AND DRIVING AN IMPROVED STAPLE 5 Sheets-Sheet 3 Filed June 19, 1952 e@ 36a Q0 36a 62a ,7 INVENTOR.

@golpe/5TM BY j' 7H. f-L9 5% Nov. 25, 1958 2,861,269

G. H. REED METHOD AND APPARATUS FOR FORMING AND DRIVING AN IMPROVED STAPLE v Filed June 19. 1952 5 Sheets-Sheet 4 @Q El@ DE? IN V EN TOR.

2,861,269v ls AND Nov. 25, 1958 G. H. REED METH ND APPARA vING AN 1 TUS FOR FORMI MPROVED STAPL 5 Sheets-Sheet 5 Filed June 19, 1952 QZQQVENTOR BY nited States Patent.

METHD AND APPARATUS FOR FORMING AND DRIVNG AN PRVED STAPLE George H. Reed, Chicago, lll., assignor to Acme Steel Company, Chi-cago, Ill., a corporation of Illinois Application .lune 19, 1952, Serial No. 294,352

s Claims. (ci. 1-82) This invention relates to an improved method and machine for forming and driving an improved staple and the present machine is a modification of that which is described and claimed in my copending application Serial No. 175,971, filed July 26, 1950, now United States Patent` No. 2,635,234, issued April 2l, 1953.

The stitching machine and staple forming method of the present invention is an improvement upon the type of machine and method in which flat stitching wire is drawn from a supply coil, fed to the stitching position, and then formed into a staple which is driven through the work to be stitched. In Stich machines it is desirable to use narrow stapling wire of small gauge which has a tendency to buckle because of its limited column strength and this has made it necessary to guide the staple carefully and to employ great precision in construction. In' many machines it is necessary to provide a retractable shoe for supporting the staple in the initial stages of the driving operation to prevent buckling of the staple legs and considerable precision of construction has been required to guide the staple to its driven position. In such a machine the buckling of the staple while being driven has often caused the operation to be arrested by theV clogging of the movable parts and any great variation in the gauge of the stitching wire has n'ot been permissible. A further disadvantage of many prior stitching machines has been that lateral curvature in the stitching wire, commonlyy known as camber, has prevented them from operating successfully.

One object of the present invention is to provide an improved staple formed of a metal strip having some or all of its parts of curved cross section whereby it has great resistance to bending and may be driven by the stitching machine without the use of a supporting shoe and without great precision in the construction of the staple forming and driving parts so that substantial variations in the gauge of the stapling wire are permitted without changing the parts of the machine.

A further object of the invention is to provide an improved method of feeding hat stitching wire to a stitching machine, and to provide an improved method of forming a staple from such stitching wire, wherein the flat wire is moved endwise toward a staple forming position and during its movement is progressively given a concavoconvex transverse curvature whereupon, after reaching the staple forming position, the transversely curved wire is cut and formed into staple-shape. Another object of the invention is to provide, in the foregoing method, the further step of removing from the wire any camber that may be present therein, the camber being removed at the same time the transverse curvature is imparted to the flat wire.

Another object of the invention is to provide an improved stitching machine comprising means for withdrawing at stapling wire from a supply, imparting a transverse curvature to the wire during its travel,y cutting otf thewire and giving its ends a predetermined shape, formice ing the severed section of wire into a staple, and then driving the staple. the staple may be caused to maintain a parallel or other desired relationship while being driven and the use of4V a supporting shoe is not required.

Still another o'bject of the invention is to provide a wire stitching machine comprising means for preventing the formation of camber during the feeding of the wire and for removing camber which may be present. A further object is to provide novel means for severing the strip and forming ends of novel form on the legs of the staples. Another object of the invention is to provide an improved staple. Other objects relate` to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the'invention will be understood from the, followingspecification taken' with the accompanying drawings in which one form of apparatus for the practice of the method is shown and one embodiment of the improved staple forming and driving machine is illustrated in connection with several embodiments of the improvedV staple and certain modifications of parts of the machine which may be employed in producing different forms of staples. In the drawings,

Figure 1 shows a partial front elevation of a staple forming and driving machine embodying the present invention with parts thereof removed and with other parts shown in vertical section;

Fig. 2 shows a perspective view ofthe preferred form of the improved staple embodying the present invention;v

Fig. 3 shows a sectional view taken on the line 3 3 of Fig. l, illustrating thc wire feeding mechanism;

Fig. 4 shows an elevational view on the line 4-4 of Fig. 3 with parts broken away; y

Fig. 5 shows a partial front elevation of the wire feeding wheels shown in Figs. 1 and 3 in engagement with the stapling wire;

Fig. 6 shows an enlarged section taken onV the line 6-6 of Fig. 5, illustrating the means for impartingea transverse curvature to the stapling wire during the feeding operation;

Fig. 7 .shows a vertical section taken on the line v7-7 of Fig. 1; V

Fig. 7A shows a section taken on the line 7A-7A of Fig. l;`

Fig; 8 shows a vertical section similar to that of the lower right-hand portion of Fig. 7, illustrating the relative positions of the parts of the anvil mechanism when it is engaged by the length of stapling wire to be formed into a staple, with the staple driver and the staple former occupying elevated positions;

Fig. 9 `shows a sectional view taken on the line 9-9 of Fig. 8;

Fig. 10 shows a sectional View similar to that of Fig. 8', illustrating the relative positions of the parts after the staple forms have been moved downwardly and the staple has been formed;

Fig. 11 shows a sectional view taken on the line 11---11` of Fig. 10;

Fig. 12 shows a sectional view similar to that of Fig. 8,A illustrating the relative positions of theparts after the anvilmechanism has been retracted 'by the downward movement of the staple driver and illustrating the driver; after it has partially driven the staple into the work;

Fig. 13 shows a sectional View taken on the line 13-13 of Fig. 12;

Fig. 14 is an enlarged elevation taken on the line 14-14 of Fig. l, illustrating the cutting mechanism for cutting the stapling wire to form the ends of the legs of the staple with the shape shown in Fig. 2;

Fig. 15. shows an enlarged side elevation of the device illustrated in Fig. 14 with parts. thereof. brokenv away, v

In this improved machine the legsY ofeillustrating the action of the cutting device in severing the stitching wire;

Fig. 16 is a view similar to that of Fig. 14 illustrating a modified form of cutting mechanism adapted to form a straight sharp edge on the stitching wire when it is cut;

Fig. 17 is a view similar to that of Fig. l5 showing the modified form of cutting device illustrated in Fig. 16;

Fig. 18 shows a perspective view of a portion of a staple having a leg which is formed at the end by the cutting mechanism illustrated in Figs. 16 and 1,7;

Fig. 19 shows an elevation of another form of cutting mechanism adapted to form a staple leg which is sharpened on one side only at its end;

Fig. 20 is a view similar to that of Fig. 14 illustrating the modified cutting device illustrated in Fig. 19;

Fig. 21 shows a perspective view of a portion of the staple having a leg which is sharpened at the end by the form of cutting device illustrated in Figs. 19 and 20;

Fig. 22 shows a partial side elevation and partial section of still another form of cutting device which is adapted to form a blunt end on the stitching wire when it is severed;

Fig. 23 is a View similar to that of Fig. 14 illustrating the modified cutting device illustrated in Fig. 22;

Fig. 24 is a perspective view of a portion of the staple formed by the use of the cutting device illustrated in Figs. 22 and 23;

Fig. 25 shows a modified construction of the staple forming, driving and clinching parts which may be substituted for the corresponding parts in the machine shown in Figs. 1 to 15, inclusive, for producing a circular stitch;

Fig. 26 shows a perspective view of a cylindrical work piece which is encircled b v a stitch produced by the moditied mechanism illustrated in Fig. 25;

Fig. 27 shows a partial elevation of the driver shown in Figs. 1 to 13, inclusive;

Fig. 28 shows an edge elevation of the driver illustrated in Fig. 27 with the lower edge thereof shown in vertical section;

Fig. 29 shows a vertical section through the work adjacent to a staple which has been formed and driven by the form of mechanism illustrated in Figs. 1 to 13, inelusive, with the type of staple shown in Fig. 2; and

Fig. 30 is a sectional view taken on the line 30-30 ofv Fig. 29.

As illustrated in the drawings, the apparatus of the invention is embodied in a stitching machine of the type disclosed in United States Letters Patent No. 644,754. granted to Matthew V. Allen on March 6, 1900, and it comprises a stapling head 25 which carries the staple forming and driving mechanism and which is adapted to cooperate with a clincher arm 26 carrying a clincher die 27 adapted to be engaged by the legs of the staple to clinch them on the underside of the parts which are stapled together. The flaps of a libre-board box, or other parts to be stapled, are placed over the clincher arm 26 and the clincher die 27 occupies a position beneath the point where the staple is to be driven.

The stapling wire 28, drawn from a spool or the like, by means of the feeding mechanism, indicated generally at 30, is fed through a guideway 31 and through a tubular shearing block 32 adjacent which it is cut ot to form a length of wire 28a adapted to`be formed into a staple above the clincher die 27. While the staple is being formed it is held by the anvil mechanism indicated generally at 34 and, as the staple is driven, this anvil mechanism is retracted to permit the driving of the staple into the work. Y

The head 25 of the machine comprises a frame or housing 35 having a face plate 36 secured to the front side thereof by screws 37. The face plate 36 is provided on its inner side with a vertical guideway 36a in which a former bar 38 is mounted to reciprocate. The former bar is provided on its outer side with'a longitudinal groove 38av ofrectangular cross section which is slidably engaged by a driving bar 40. The former bar 38 has secured to the lower end thereof two staple formers 41 which are held in place by screws 42 and which are provided on their opposed faces with longitudinal grooves 41a adapted to engage the projecting portions of the length of stapling wire 23a to cause the formation of a U-shaped staple in cooperation with parts of the anvil mechanism 34 when the former bar 38 is moved downwardly.

The driving bar 40 has keyed to the lower end thereof a staple driver 43 which is adapted to engage the head of the U-shaped staple and drive it downwardly through the work while at the same time causing the retraction of the anvil mechanism as hereinafter more fully described.

For the purpose of actuating the former bar 38, it is provided between its ends with an aperture engaged by a threaded pin 44 which is held in place by a nut 45 and which is provided with a cylindrical extremity 44a having mounted thereon a roller 46 adapted to travel in a continuous groove 47a formed in a cam 47. This groove has the irregular contour shown in Fig. l and the cam has a hub portion 47b which is journaled in a bearing 35a formed in the housing 35. The hub portion 4'7b is keyed to a shaft 4S which is also journaled in a bearing 'formed in the housing 35 and which is adapted to be driven at uniform speed by an electric motor or the like. Thus, during the rotation of this shaft the cam 37 is rotated and the former bar .3S is actuated to cause the formation of a staple during each rotation of the cam.

In order to effect the reciprocation of the driving bar 40, this bar is provided at its upper end with a transversely extending pin 40a upon which is journaled a bushing 49 secured in the upper end of a crank arm 50. The lower end of this crank arm is provided with a transversely extending pin 51, shown'in Fig. 7A which is journaled in a sleeve 52a formed in the end of a link 52. This sleeve is in turn journaled in a cylindrical recess 47o formed in the face of the cam 47 at a point displaced radially from the axis of this cam. Thus, when the cam 47 is rotated, the pin 51 revolves about the axis of the cam and thereby causes the crank arm 50 to effect a reciprocation of the driving bar 40. The recess 47s1 in the cam is so located that the downward movement of the driving bar 40 will be effected in proper timed relation to the movement of the former bar 3S so that a staple will be formed and will be in readiness to be driven when the staple driver 43 carried by the driving bar 40 arrives at a position where it is about to engage the formed staple.

The wire feeding mechanism shown particularly in Figs. l, 3, 4, 5 and 6, is actuated by the previously mentioned link 52 which is actuated by the cam 47. This link is pivotally connected at 54 to a lever 55 which has its lower end pivoted at 56 on a plate 57 mounted for pivotal movement on the casing 35. The reciprocation of the link 52 in response to the rotation of the cam 47 causes an angular oscillation of the lever 55 which actuates a curved link 58 pivotally connected to the upper end of this lever. The other end of this link is pivotally connected at the point 59 to a crank arm 60 which actuates the wire feed mechanism through an overrunning clutch of the type disclosed in United States Letters Patent of Howard G. Allen, No. 1,513,021, dated October 28, 1924, `whereby an intermittent feeding movement isV imparted to the stitching wire 28.

The crank arm 60 is rotatably mounted upon a shaft 61 located in the housing 62 of the feed mechanism. The crank arm 60 has a pin 63 projecting from the side thereof to engage a slot 64a formed in the side of the clutch driving ring 64 which is mounted to rotate about a clutch disk 65 fixed upon the reduced extremity 61a of the shaft. The disk 65 is provided with side plates 65a which are secured thereto and which overlap at their outer edges the inner margin of the ring 64, as shown in Fig. 3. The disk 65 and its plates 65a are retained against endwise movement of the shaft 6I by a cap member 67 which is secured to the end of the shaft. of spaced pockets 65b in. each of Whichthere is mounted a cylindrical roller 66. These pockets are provided with bottom walls 65e which yare at right angles to radii of the disk and are so positioned that they converge with the surrounding annular surface 64b of the ring 64 toward one end of the pocket. The roller 66 is thus adapted to wedge between the surface 65C and the surface 64b as it moves toward one end of the pocket but to be released as it moves toward the other end. A coil spring 68 is mounted in each pocket to press the roller 66 normally toward the small end of the pocket and when the ring 64 is rotated in a direction to urge the rollers 66 toward the small ends of the pockets, ay driving connection is thereby established between the ring 64 and the disk 65 which is fixed upon the shaft 61. When the crank arm 60 is moved in the reverse direction the ring 64 tends to move the rollers 66 toward the larger ends of the pockets 65h so that the ring 64 then moves around the disk 65 and the shaft 61 remains stationary. In this way, an intermittent rotary motion is imparted to the shaft 6l.

This intermittent motion is made use of for eifecting an intermittent feed of the stitching wire 28 which passes between two feed wheels 74B and 71. These feed wheels are fixed on the hubs of two gears 72 and 73,V respectively, which mesh with each other and cause the feed wheelsto be rotated in reverse directions. The gear 72 is secured upon the end of the shaft 61 and the other gear 73 is journaled upon a shaft 74 which is jo-urnaled in the frame member 7S in which the shaft 61 is journaled. The feed wheel 70 is provided around its periphery with an annular groove 76a which is engaged by an annular rib 71a formedon the periphery of the feed wheel 71. The stitching wire 23 passes through the' groove 74M in the direction of the arrow 76, shown, in Fig.' 5, and is thereby caused to conform to the curva-A ture ofthe bottom wall 76h of the groove and. to the corresponding curvature of the annular surface 71b of the rib 71a. The curvature of thev surface 70h and 71h is such that the metal of the stitching wire i-s stressed beyond the elastic limit of the metal so that a permanent transverse curvature is thereby imparted to the stitching wire and it has this transversely curved form as it enters the guide 31.

As the stitching wire 28 passes between the feed Wheels 70 and 71 it is substantially confined between the surfaces 7tlb and 71b, with only a` slight clearance, and the edges of the metal strip are confined between the side walls 70C of the annular groove 70a. As shown particularly in Fig. 5, the stitching wire is thus confined betweenthe side walls 70e through a substantial distance. Thus, by transversely curving the stitching wire as it is conned between the surfaces '70b and 71h, it is' found that any camber which may be in the strip as it comes from the supply reel is substantially reduced. The gears 72 and 73 are xed' on the shafts 61 and 74, respectively, so'that they have a limited endwise movement, forexample, from .00 to .010, so that as themetal stitching wire advances to the feed wheels from the' supply reel, the feed wheels tendY automatically to' align themselves with the metal strip and thusk minimize'the possible formation of camber due to unequal distribution ofpressure between-the contacting'portions of` the feed wheels as the strip moves betweenv thema Inpractice, the clearance between the Walls of the groove 70a and the annular rib 71a^may be on the order of .O Ol to v.002 and it is only necessary that the endwise movement of the feed wheels 70 and 71 be' not any greater than-the total of the clearanceson both-sidesfofk the` rib 71a.

Since a transverse curvature is imparted to the-stitch ing wire throughout its length as: it passes between` the feed wheels, it is adapted for use informing a. U.-shaped Stapleg-such as the staple 801 shown in. Fig. 2, which. hasa The disk. 65' is providediwithv arr` annular'series top: Wallittltr'andi:parallellegsV 801i. All parts of this; staple have a curved cross section including the cornerportionslc:and the ends of the legs 80b are adapted to be sharpened in the process of cutting off'the stitching wire, in the manner hereinafter described, thus producingsharpened extremities Stia which, in this embodiment, are sharpened on both edges so that they are of V-shaped cross section. A staple of this formation has the advantage that the top wall 30a is relatively stiff,

and is thereafter adapted to resist any bending under the influence of the staple driver. Also, the legs Sb have the advantage that they have substantial column strength so that they resist buckling while being driven, thus making it unnecessary to use the supporting shoe which has heretofore been mounted within the staple to be gradually retracted as the `staple is driven. Due to their stilfness and their sharpened extremities, the staple legs may be driven through materials of substantial hardness with which stitching wire has not heretofore been capable of use and, when driving the staple legs through wood, for example, it is not material whether the staple legs extend parallel to or transversely of the grain of the wood.

For the purpose of cutting off th-e increment of stitching wire 28a which is projected through the anvil mechanismV 34, as shown in Fig. l, the machine is provided with a cutting blade 82 which is attached by a screw 83 to a projecting portion 84a of a bar 84 mounted toreciprocate in a casing 85 on which the stitching wire guide 32 is formed. The casing 85 is attached to the face plate 36 and the bar S4 is mounted for vertical sliding movement therein, being held normally in its upper position by 'a coil spring 86 which engages a tubular bore formed within the bar, and rests at its lower end on the lower wall of the casing immediately above the stitching wire guide 32.

The cutting blade 82 is provided at its lower end with an arcuate cutting edge 32a which is of V-shaped cross section, as shown in Figs. 14 and 15. When the bar 84 is moved downwardly against the compression of the spring 86, this cutting edge is adapted to cooperate with a stationary cutting die S7 which has an annular V-shaped cutting edge 87a and which is provided with a cylindrical stem 87b mounted in a bore 32h formed in the stitching wire guide. The stationary die 87 is held in fixed position in the guide 32 by means of a setscrew 88 sho-wn particularly in Fig. 14. By releasing the setscrew 88 the stationary cutting die 87 maybe rotated to bring a fresh cutting edge to position to cooperate with removableblade 82. The stitching wire 28 advances from the guide 31 to a passage 32a formed in the guide 32 and it emerges immediately above the stationary die 87, as shown in Fig. l. When the cutting blade S2 is moved downwardly the stitching wire 28 is pressed downwardly against the stationary die 87 and the blade cooperates with the die to cut off the stitching wire 28 and form the arcuate;

At a proper time in the cycle of operations, the bar 34.

is moved Vdownwardly to sever the stitching wire and this is effected by an adjustable pin 96 mounted on an arm 91 which is iixed on a shaft 92 which is journaled in the face plate 36and arranged toy extend into the interior of the housing 35. Within this housing a curved operating arm 93 is secured ontheshaft 92 and the tip of this arm is adapted to be engaged by a projection 59a on the lower end of the link 56 so that as the shaft 92 is momentarily rocked in a counterclockwise direction, as viewed in Fig.

l,.the bar 84y iscaused to be moved downwardly against; 75. the; compression; of the spring 86Y andv thereby cause-the* blade 82 to cut olf the length of stitching wirer28a. After Y the wire is cut ot, the former bar 38 is moved downwardly by the cam 47 to form the length of wire 28a into a U-shaped staple 30 having the form shown in Fig. 2, and the driving bar 40 then descends to cause the driver 43 to project the staple downwardly through the work.

'For the purpose of adjusting the length of the increment of stitching Wire 28a which is fed by the wire feeding mechanism 30 upon each rotation of the cam shaft 48, a handle 95 is provided to turn the plate 57 about its pivot 96 and thus vary the position of the pivot 56 of the lever 55, thereby varying the amplitude of movement of the crank arm 60 upon each reciprocation of the link 52. Also, the plate S7 is provided with an arcuate slot 57a engaged by a roller 97 mounted on a bar 98 attached to the casing 85 and this casing is slidably mounted upon the face plate 36 so that if the plate 57 is adjusted to increase the length of the increment of stitching wire 28a which is fed through the anvil mechanism 34 upon each rotation of the cam shaft 48, the casing 85 will at the same time be adjusted in order to vary the spaced relation of the cutting blade 82 and the shearing die 87 with respect to the anvil mechanism so that both legs of the staple to be formed will be of substantially the same length. These features of adjusting the length of the cutoff sections of staple wire and causing the legs of the staple to be o-f equal length do not in themselves constitute parts of the present invention.

The anvil mechanism 34 which holds the cut-off section of wire 28a when it is severed by the shearing device, is shown particularly in Figs. 7 to 13, inclusive, and cornprises the anvil die 100 which is mounted at the tower end of the anvil carrier 101 pivotally mounted by a pin 102 in a chamber 10351 formed in the lower end of a cover block 103 which is secured by screws 104 to the face plate 36. The anvil 100 and the lower part of the carrier 101 are normally caused to swing toward the path of movement of the driving bar 40 by the action of a leaf spring 10S which has its lower end engaging a recess 101a formed in the anvil carrier. The side walls 101b of the recess 101a are bent inwardly to interlock with the curved portion 105:1 of the spring which is adjacent to its lower extremity 105k. r1`he upper end of the spring 105 extends into a recess 103]: formed in the upper inner side of the block 103 where it coaets with the bottom edge of the face plate 36, so that it operates normally to swing the lower end of the carrier 101 with its anvil 100 to a position where 4a V-shaped projection 101C, formed on the anvil carrier, lies in the path of movement of the staple driver 43, as shown, for example, in Fig. 8. At this time the rib 10M, which extends upwardly from the projection 101C, is positioned between the forming dies 41, as shown in Figs. 8 and 9. This spring 105 may be readily removed for replacement by pulling on its upper end.

The anvil 100 has a part 100a over which the cut-off piece of wire 28a is adapted to be bent to form a staple of the form shown in Fig. 2. This part 100a is carried by a small block 10017 which is pivotally mounted by a pin 107 between the flanges 101e which constitute the lower extremity of the anvil carrier 101. The part 100b of the anvil die has a tail portion which extends upwardly and rearwardly from the top of the part 100:1 and this tail portion has an inclined surface 100C which is adapted to engage an inclined surface 101]c formed on the anvil carrier 101 between the ilanges 101e, thereby limiting the downward movement of the die portion 100e during the formation of the staple. A coil spring 108 is mounted in a recess formed in the rearwardly extending path 100b of the anvil and in the lower part of the anvil carrier and this spring tends normally to move the anvil die 100a to the position shown in Fig. 8 where the pressure of the spring 108 is adapted to cause the anvil to grip the section 28o of the wire between its top face and the lower face lof the projection 101e` formed on the carrier. The side of the part 101C is provided with a notch or guideway 101g'of V-shaped cross section which is adapted to engage the end of the wire 28 as it is being fed by the wire feeding mechanism 30 in order to direct the wire into proper position beneath the portion 101C and above the portion 100:1 of the anvil. The gripping of the wire 28a by the spring actuated anvil 100 continues until the anvil is moved downwardly during the staple forming operation to the position shown in Fig. l0.

After the wire has been positioned in the anvil mechanism in the manner illustrated in Figs. l, 8 and 9, and after the section 28a of the wire has been cut ol by the downward movement of the cutting blade 82, the cam 47 actuates the former bar 38 to cause the former dies 41 to move downwardly and engage the projecting ends of the cut-off piece 28a of the wire. These end portions of this piece of wire pass into the grooves 41a formed in the former dies and, as the former bar 38 moves downwardly, they are bent downwardly to form a U-shaped staple as shown in Figs. 10 and 11. As this downward movement proceeds, the anvil 100 is adapted to tilt about its pivot 107 until the surface 100e engages the surface 101f, as shown in Fig. l0, thus causing the anvil to be rmly supported during the formation of the staple. This-movement of the anvil separates the part 100a of the anvil from the projection 101e of the carrier so that the staple is free to move out of engagement with the anvil. This separation of the anvil and the staple is then effected by the downward movement of the staple driver 43 which then takes place in response to the downward movement of the driving bar 40. As the driving member 43 moves downwardly it engages the inclined front face of the part 101e of the anvil carrier and cams this member 101 tov ward the right, as viewed in Fig. l0, against the action of the leaf spring 105. As the driving member 43 moves downwardly the anvil carrier 101 and the anvil 100 are moved to the position shown in Fig. l2, the staple is disengaged from the anvil 100, and the staple is then driven downwardly by the driver 43 through the work which is supported on the clincher die 27. As the staple is driven, the anvil carrier and the anvil are retained in the retracted position shown in Fig. l2 by the presence of the driving member 43 which then coacts with the tip of the projection 101e of the anvil carrier.

After the staple has been driven the driving bar 40 is moved upwardly following the former bar 38 which will have been previously moved upwardly by the action of the cam 47. When the driving member 43 has moved upwardly beyond the projection 101C of the anvil carrier, this carrier is again moved by the spring 105 to the position shown in Fig. 8 and the anvil 100 will be moved by the spring 108 to the position shown in Fig. 8 where it engages a new length of wire fed by the mechanism 30. Thus the cycle of operations may again be repeated with the feeding of a section of wire, the cutting ot of that section, the forming ofthe staple, and the driving of the staple taking place during each rotation of the cam 47. The machine is provided with mechanism, not shown, for insuring that the cam 47 will rotate a single complete revolution during each period when a staple is formed and driven so that all of the parts start and stop their operations in the same relative positions in each cycle.

The staple driving member 43 described above preferably has a lower edge 43b which is arcuate in both right angular directions, as shown in Figs. 27 and 28, so that it conforms to the curvature of the stitching wire 28 and to the top wall 80a of the finished staple in both directions. This prevents any substantial deformation of the'staple while it is being driven so that when the staple has been driven and clinched, as shown in Fig. 29, its top wall retains substantially its initial formation and the edges 80e of the staple become embedded in the material 110 which is being securedby the staple. Due to the stiffness imparted to the legs of the staple by the transverse curvature the legs penetrate the material 110 in parallel .paths and do notdeviate from their intended relationshipso that after they have:penetrated the material being stapledjand have been. clinched. by engagementwith the stapling die 27, the legs'are directed toward each other las shown at 80j in Fig. 29, and their extremities are turned-upwardly into the. material 110 so that they do not catch on surrounding objects. Although no supporting shoeis provided for the staple during the driving operationithas been found that the use of this supporting device is unnecessary because any tendency of the staple to collapse either by the downward bending of the head of the staple or by the inward buckling of the legs is effectually overcome by the added strength derived from thetransverse curvature of the stitching wire which is progressively created in the wire during the feeding operation;

In the embodiment' of the. invention which has been described above the sharpened ends 80d of the staple are arcuate in cross section, thus facilitating the driving of the staple and the penetration of the material being stapled at. the conclusion of the clinching operation. However, there may be instances where other forms of staple legs may be desired and, iny Figs. 16 and 17 of the drawings, there; is illustrated a modified form of cutting mechanism comprising a cutting blade 112 having 4a straight cutting edge 112a which is beveled on both sides so that it forms aninclined surface on both ends of the wire which are severed. This blade 112 is adapted to cooperate With a stationary cutting die 113 which is similar to the die 87 exceptthat the cutting head is rectangular in cross section and has four V-shaped cutting edges 113m which are similar in formation to the cutting edge 112a. This cutting die113 is mounted upon astem 114 and is adapted to be secured in adjusted position by a setscrew 115. By releasing the setscrew any one of the four cutting edges 113a may be brought into operative position. With the use of cutting devices of the form shown in Figs. 16 and 17, there may be produced a staple 116 of the form shown inFig. 18-where theelegrllbof the staple has a straight sharp-edge 116C of V-shaped cross section.

Another form ofY cutting mechanism is shown in Figs. \19 and 20 where a cutting blade 120 cooperates with a stationary die 121`v secured` inoperative position by a setscrewV 122. The cutting blade 120 has a straight cutting edge 121m of V-shaped cross section and the stationary cutting die 121 isprovided with a flat top surface 121a adapted to support the stitching wire on the underside when the cuttingV blade 120 moves downwardly to sever thewire. flatten the stitching'wire Iat the place of cutting and since the-cutting-occursonlyonV one side of the wire, the leg 123a of the resulting-staple 123, shown in Fig. 21, has a single. beveled edge 123e at its extremity. This form of staple leg may be of advantage when itis desired to cause the staple legs to converge upon each other as they are being driven.

Another form of cutting mechanism is shown in Figs. 22 and 23 where the movable cutting blade 125 serves to shear oi the stitching wire at the place where it emerges from the passage 32a in the shearing guide 32. The shearing guide thus serves as a stationary die and the resulting staple leg 126b, shown in Fig. 24, has a blunt end 126C which may be desirable when the stapling machine is being used for stapling very light material.

The stitching machine of the present invention may also be employed for forming a circular staple or collar surrounding a cylindrical article or group of articles to be secured or bound. A modied construction capable of producing and driving staples or stitches of this form is shown in Fig. 25 Where the former dies 131 have substantially the form previously described but the driver 133 has an arcuate lower end 133e to conform to the semi-circular top wall of the staple 134. The clinching die 135 his a similar semi-circular clinching surface 13511 so that when the cylindrical object 136, shown in Fig. 26, is seated on the clinching die 135, the operation The use ofthe straight cutting edge servestoY cular form shown at 13.4a1in1Fig.- 26 wherev it surrounds: and is` partiallyembedded' in the material'.` ofl the* object 136.y

From the foregoing description it will beseen'thatAv theY present invention provides means whereby the flat.'v

when staples are formed from the wire and drivenvinto" the work. These advantages include the fact that thelegsof the staple are straight and have considerable column strength so that they have littletendency to bucklev when driven, thus making it unnecessary to provide a staple supporting shoe as in prior machines. Due to the straightness and stiffness ofthe staple legs, it is possible to use stapling wire of much smaller gauge and width than that required in prior conventional machines and it is possible to drive staples through work piecesv having such resistance that they formerly could not be penetrated by staples formed from flat wire and driven by the prior conventional machines. For illustration, the conventional stitching machine can stitch through a `maximum of three thicknesses of solid berboard, each having a thickness of .100", with the use of at stitchingwire having a thickness of .020" and a width of .103". In contrast'withthis performance, the stitching machine of the present invention can stitch through six thicknesses of solid berboard each'having a thickness of- .100 whenA using stitching wire formed into arcuate shape and having a thickness of` only .014 and a width of .103. Flat stitching Wire having a thickness of only .014" does notfgive satisfactory resultsvin a conventional stitching machine even when'the staple is driven only through a single thickness of berboard having a thickness of .100".

Further, it has been found that a conventional stitch-- ingmachine using flat stitching wirey can stitch through three thicknesses of double wall corrugated fiberboard o'f 600 lbs. tensile test using a stitching wire which is .028 thick and .103 wide but'with rather inconsistent results'. In contrast with this, staples of arcuate cross section and having straight legs produced by the machine of thepresent invention may be consistently driven when the stapling Wire is only .017 thick and .103" wide. Also,y it has been found that conventional stitching machinesy using flaty stitching. wire cannot be used to stitch together the layers of cloth and ber which are employed inthe. manufacture ofbuflingrwheels where three thick; nesses of solid fiber eachhaving a thickness of .080 aresecured to twelve thicknesses of cloth having a compressedthickness of about .200. the layers of such an article together with the conventional stitching machine using at stapling wire, it has been found that the resistance is so great that the staple legs buckle instead of penetrating the work but the machine of the present invention using staples formed as described above has been found to work satisfactorily on this type type of Work with stapling wire having a thickness of .017 and a width of .103.

Another advantage of the present invention is that satisfactory stapling operations may be performed with a lesser compression of the work piece than that required with standard stapling machines employing flat stitching wire. In the operation of the machine described above and in conventional stapling machines, it is common practice for the staple formers to engage the work piece after bending the legs of the staple and to compress the work piece lagainst the staple clincher while the staple is being driven. This has heretofore resulted in some injury to the surface of the Work piece by the pressure of the staple formers but, with the present invention, much less pressure of the formers is required while permitting a satisfactory driving of the staple legs of arcuate cross In attempting to stitch 11 sectionand smaller dimensions so that injury to the surface of the work piece is eliminated.

-A1though several forms of the improved staple of the present invention have been shown and described in connection with the illustration of one form of machine for forming and driving these staples, with modifications of the machine adapted for use with diierent forms of staples, it will be understood that the staple and the forming and driving machine may be modified in other ways without departing from the scope of the appended claims. The novel features of the stitching machine described above which are not claimed herein are claimed in said copending application Serial No. 175,971, now U. S. Patent No. 2,635,234.

I claim:

1. The method of forming staples one after another from a continuous length of fiat stitching wire, comprising the steps of intermittently advancing said wire endwise toward a staple forming position, progressively imparting to said wire during the movement thereof a concavo-convex transverse curvature, severing a predetermined length from the leading end of the transversely curved portion of the wire upon the termination of each advancing movement thereof, and then bending said predetermined length into staple shape.

2. The method of forming staples one after another from Ia continuous length of at stitching wire, comprising the steps of intermittently advancing said wire endwise toward a staple forming position, progressively removing camber from the wire and imparting a concavoconvex transverse curvature thereto during the endwise of the wire upon the termination of each advancing move- Y ment thereof, and then bending said predetermined length into staple shape.

3. The combination in a wire stitching machine, of means for intermittently feeding transversely curved stitching Wire in an endwise direction, a die'over which said transversely curved wire is fed, a cutting member cooperating with said die to cut said transverselycurved wire into lengths, said cutting member and said' die having cooperating cutting surfaces conforming in shape to the transverse curvatureof said wire for maintaining said curvature in said wire during the cutting thereof, and means for forming said lengths into staples while maintaining transverse curvature therein.

4. The combination in a wire stitching machine, of means for intermittently feeding transversely curved stitching wire in an endwise direction, a die over which said transversely curved wire is fed, a cutting member cooperating with said die to cut said transversely curved wire into lengths, said cutting member and said die having cooperating cutting surfaces for maintaining transverse curvature in said wire during the cutting thereof, and means for forming said lengths into staples while maintaining transverse curvature therein.

5. The combination in a wire stitching machine, of means for intermittently feeding transversely curved stitching wire in an endwise direction, a die over which said transversely curved Wire is fed, a cutting member cooperating with said die to cut said transversely curved wire into lengths, said cutting member and said die having cooperating arcuate shaped cutting surfaces for maintaining said transverse curvature in said wire during the cutting thereof, and means for forming sai-d lengths into staples while maintaining transverse curvature therein.

6. The combination in a wire stitching machine, of a pair of feed wheels for withdrawing substantially at stitching wire from a supply and feeding ity endwise, one of said wheels having a relatively deep annular groove having radially extending side walls between which the wire passes and the other of said wheels having an annular projection extending into said groove, and meansfor rotating said Wheels, the bottom of said groove and the outer periphery of said projection having cooperating complementary curved surfaces engaging the wire for imparting a transverse curve thereto, said radially extending side walls of said relatively deep groove being spaced apart a distance only slightly greater than the width of the wire for closely confining the lateral edges of the wire both well ahead of and behind the point of contact of ksaid curved. surfaces with the wire, whereby lateral curvature is removed from the wire at the same time that a transverse curvature is imparted thereto by said curved surfaces. Y

References Cited in the tile of this patent UNITED STATES PATENTS 315,124 Chisholm Apr. 7, 1885 527,184 Richey Oct. 9, 1894 1,415,408 Scott May 9, 1922 2,099,532 Pierce Nov. 16, 1937 2,147,976 Harrison Feb. 21, 1939 2,191,869 Stone Feb. 27, 1940 2,216,453 Paulin Oct. 1, 1940 v 2,314,184 Zeruneith Mar. 16, 1943 2,370,215 Nilsen Feb. 27, 1945 2,380,786 Percoco July 31, 1945 2,392,160 La Place Jan. l, 1946 2,565,983 Nelson Aug. 28, 1951 2,594,201 Nasmith Apr. 22, 1952 VFOREIGN PATENTS 4,906 Great Britain Feb. 9, 1901. 

